PRINCIPLES OF STOCK FEEDING 



51 



called to this table again when the dis- 

 cussion of the compounding of rations 

 for animals is taken up. 



Determination of digestibility — The 

 digestibility of feeding stuffs is deter- 

 mined by feeding animals regularly for 

 a considerable period food which has 

 been carefully analyzed. The feces are 

 collected during this period and ana- 

 lyzed. The difference between the 

 amount of food fed and the amount of 

 undigested matter found in the feces is 

 taken to represent the amount digested 

 by the animal. The digestibility of the 

 different feeding stuffs as given in tables 

 of digestibilifr 0, has been determined in 

 this manner. 



The greatest number of digestion ex- 

 periments has been made with rumi- 

 nants, a less number with swine and 

 horses, and a few with poultry. The 

 coefficients of digestion, i. e., the percent- 

 age digestibility of feeding stuffs, for 

 these different classes of animals, are 

 shown separately in the tables above re- 

 ferred to. 



Digestion by different animals — As 

 regards different kinds of animals, 

 cattle, sheep and goats appear to digest 

 the same foods equally well. This is 

 especially true of the more easily di- 

 gested foods. In the case of woody, dif- 

 ficultly digested foods, cattle digest a 

 larger percentage than sheep. Horses, 

 probably on account of the simpler or- 

 ganization of the stomach, do not digest 

 most feeding stuffs as well as the ru- 

 minants do. They digest oats and corn 

 and in general the protein constituents 

 of feeds practically as well as sheep, but 

 not the crude fiber or crude fat. Swine 

 digest corn, barley and some other 

 grains as well or better than ruminants. 

 They do not digest the crude fiber and 

 fat of most feeding stuffs as well as 

 ruminants do nor the protein of green 

 forage as well. 



Different breeds of the same species 

 of animal digest feeds apparently 

 equally well, and young animals appear 

 to digest the better grades of coarse 

 feeds and grains equally as well as older 

 animals of the same kind. 



Factors affecting digestion — There 

 are a number of factors affecting the 

 digestion of feeding stuffs which are 

 within the control of the feeder and 

 these he should know. 



Palatability — A palatable ration fa- 

 vors digestion probably because of a 

 greater flow of the digestive juices which 



occurs when foods are eaten with a rel- 

 ish. It is believed that the success of 

 many feeders is due, in a large measure, 

 to their great care in the preparation 

 of rations to have them appetizing and 

 palatable. The more palatable the ra- 

 tion the more within limits will the ani- 

 mal eat, and the more the animal eats 

 and digests the greater will be the 

 amount of flesh or other animal products 

 produced. 



The stage of growth at which fod- 

 ders are harvested have a marked in- 

 fluence on their digestibility. Young 

 growing plants contain relatively more 

 protein and less woody fiber than older 

 plants and are more easily digested. As 

 plants approach maturity there is gen- 

 erally a translocation of a large portion 

 of the protein, starch and fat to the 

 seeds, leaving the hard, woody portion, 

 or crude fibers, in the stems. This is 

 why straw made from crops cut when 

 the grain is ripe is so greatly inferior 

 in feeding value to the hay made from 

 the same grains if cut when the grain 

 is in the early dough stage. Hay made 

 from ripe grasses is no better than straw. 



The yield of early cut plants is very 

 much less than from mature plants, so 

 that the total amount of digestible nu- 

 trients is greater as the plants approach 

 maturity. The greatest amount of di- 

 gestible food in the grasses is obtained 

 about the time, or soon after, they come 

 into bloom and this is the time they 

 should be cut for hay. 



Cured hay appears to be as easily di- 

 gested as the fresh grass from which it 

 is made. In curing, however, there is 

 usually considarable loss from the dry- 

 ing up and rattling off of the leaves and 

 finer parts of the plants thus leaving a 

 larger proportion of woody fiber. Prac- 

 tically, therefore, cured fodder is not 

 quite so digestible as green fodder. 



Cured or partially cured hay that has 

 been exposed to rain is decreased in di- 

 gestibility. The rain leeches out some 

 of the more soluble constituents of the 

 hay leaving the more undigestible parts. 

 The fermentation of hay in the mow, 

 corn in the shock, or grain in the bin, 

 also decreases digestibility. Silage is 

 not as digestible or as nutritious as the 

 green fodder from which it is made. 

 Long stored hay also is slightly less di- 

 gestible than fresh hay. 



Special practices, as wetting feeds, 

 cooking, steaming, etc, have been shown 

 by many American and German experi- 



